From the editors | Nature Reviews Cancer

Access through your institution Buy or subscribe The search term 'cancer stem cells' identifies 31,606 papers in PubMed, a clear illustration, if one was needed, of how popular

this area of cancer research currently is. But, what do we really know about the biology of cancer stem cells? How closely are they related to normal tissue stem cells and does it follow

that the cancer stem cell is the cell of origin of the cancer? Since the identification of leukaemic stem cells, the race has been on to identify similar cells within tumours that arise in

solid tissues. This has now been successfully achieved for several organs, including the brain. However, because various techniques can be used to identify and purify these cells, it is not

clear that all cells that are labelled as cancer stem cells really are cancer stem cells. Angelo Vescovi, Rossella Galli and Brent Reynolds (on page 425) argue that a set of brain tumour

stem-cell characteristics needs to be agreed on to enable researchers to work from the same page. Many argue that cancer arises owing to the transformation of a normal tissue stem cell, so

we also require a similar clarification for normal tissue stem cells. However, as Vescovi and colleagues point out, the cancer stem cell might instead arise from a more differentiated cell,

a progenitor cell for example, that has acquired stem-cell-like functions. So we need to be able to clearly distinguish between the normal and the cancer stem cell. But this still leaves us

with the question of what is the cancer cell of origin, is it the cancer stem cell or does the cancer stem cell arise from the cell of origin? Hopefully, as the characteristics of normal and

cancer stem cells become more clearly defined, the true cellular origin of many cancers will become apparent and so will the cellular characteristics that will be effective therapeutic

targets. This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 12 print issues and online

access $209.00 per year only $17.42 per issue Learn more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which

are calculated during checkout ADDITIONAL ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support RIGHTS AND PERMISSIONS Reprints and

permissions ABOUT THIS ARTICLE CITE THIS ARTICLE From the editors. _Nat Rev Cancer_ 6, 415 (2006). https://doi.org/10.1038/nrc1925 Download citation * Issue Date: June 2006 * DOI:

https://doi.org/10.1038/nrc1925 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a shareable link is not currently

available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative